1. Field of the Invention
The present invention relates to a magnetic recording medium used for a magnetic recording reproduction device such as magnetic disk system and the like, capable of high density recording, and manufacturing method therefor.
2. Related Background Art
Magnetic recording media have advanced in recording density in recent years. A magnetic recording method is being transferred from an in-plane recording method to a vertical recording method. The in-plane recording method is such that magnetic field is applied along a magnetic recording surface. The method however has a limitation on the increase of recording density in that increase in recording density decreases one-bit magnetic domain, canceling out between peripheral magnetic domains, which losing magnetic force. The vertical recording method is such that a magnetic field is applied perpendicular with respect to a recording surface, so that a magnetic domain can be widened, less influenced by demagnetizing field, thereby recording density can be increased. Nevertheless, further high density recording has been demanded even in the vertical magnetic recording method. In a conventional recording medium of which layer is uniform, magnetic flux from a recording head spreads to targeted recording tracks as well as their adjacent tracks, which can disturb recording state of the adjacent tracks. This disturbance causes a lateral crosstalk noise at the time of reproduction of recording.
For this reason, a large number of improvements have been proposed until now. U.S. Pat. No. 6,055,139 puts forth a proposal that magnetic characteristics are changed by varying film thickness. Another proposal is that recording layers are directly patterned because it is preferable to magnetically separate recording tracks. Japanese Patent Application Laid-Open No. 2003-30827 states that resist and dry etching process are not required, instead of which recording layers are subjected to light beams, electron beams, or ion beams to locally heat the layers, thereby magnetization is decreased by diffusion of materials from a diffusion species layer underlying the recording layer to a recording layer, which enables magnetically separating recording tracks.
In steps for magnetically separating recording tracks in the aforementioned recording layer, direct dry etching is performed by, needless to say, using light beams and the like as an assist source to promote mutual diffusion through other materials after the formation of the recording layer. Methods of decreasing magnetization may damage regions to be used as recording tracks. For that reason, there has been demanded a method of allowing magnetic separation in the forming process of a recording layer.
The purpose of the present invention is to provide a novel magnetic recording medium which less damages the recording layer and of which recording tracks are fully magnetically spaced apart and manufacturing method therefor.